Liquid crystal display, due to its advantages of low radiation, less power consumption, thinness, light weight and the like, has been applied more and more widely. Currently, liquid crystal display technology has become a mainstream display technology.
In a liquid crystal display, since liquid crystals do not emit light themselves, but regulate light instead, it is necessary to provide a liquid crystal display panel with a backlight module so that images can be displayed on the screen of the liquid crystal display. A light guide plate is one of the key components of the backlight module, and is used for transforming light emitted from multiple point light sources or line light sources into a surface light source and then casting the transformed light onto the display panel. In the above backlight module, a ratio of a distance between the light sources and an active area of the display panel to a pitch between adjacent light sources, that is, an A/P ratio, is a key parameter that affects luminance uniformity in respective areas of the light guide plate. When the A/P ratio is small, that is, when the distance between the light sources and the active area of the display panel is small and the pitch between adjacent light sources is large, a hotspot phenomenon that some areas on the light guide plate are significantly darker than the other areas on the light guide plate and dark areas are formed may occur.
In order to alleviate the above hotspot phenomenon due to small A/P ratio, generally, a predetermined dot-pattern micro-structure may be formed on the light guide plate by microstructure forming processes, such as injecting, hot pressing, ink-jetting and the like so as to enhance scattering of light on the light guide plate, and further to improve luminance uniformity in respective areas of the light guide plate.
However, with the development of the liquid crystal display toward narrow bezel and low power consumption (i.e., fewer amount of light sources), the distance between light sources and the active area of the display panel becomes smaller, and the pitch between adjacent light sources becomes larger, which results in smaller A/P ratio. When the A/P ratio is smaller than a certain value, dark areas are inevitably generated on the light guide plate to cause hotspot phenomenon, even if the dot-pattern micro-structure is provided on the light guide plate. By taking a display panel applicable to a notebook computer as an example, practice has proven that, when the A/P ratio is smaller than 0.65, the hotspot phenomenon will occur on the light guide plate, and cannot be alleviated by providing the dot-pattern micro-structure. In this case, in order to further alleviate the hotspot phenomenon, a shading tape is generally attached to U-bending portion of a back plate below the light guide plate, and a side of the shading tape facing the light guide plate is all white or black so that the shading tape may absorb light emitted from the light sources or reflect light emitted from the light sources to the light guide plate, to decrease or increase luminance of a corresponding area on the light guide plate.
However, in practical applications, the side of the above shading tape facing the light guide plate is generally a smooth plane, which results in that, when such shading tape is used to attenuate or enhance the luminance of a corresponding area on the light guide plate, the luminance of the area is attenuated or enhanced by the same magnitude, that is, the shading tape cannot enhance the luminance of an area with low luminance on the light guide plate and attenuate the luminance of an area with high luminance on the light guide plate in a targeted manner.